S7horton got it right on the money about sending only one channel to each amp. You either need the y-adapter or two sets of ICs.
I also agree with Eldartford about the effects on the power supplies when running the amps in bridged mode. But you need to remember that you are effectively cutting the load seen by the amp in half when running amps in bridged mode. The effects of pulling more on the power supply from one side vs. the other as with the vertical connections can be compensated for by periodically switching the side that drives the woofers. In my brief experience with bridging I have found that the amps run hotter and it just doesn't sound as good. This is very much dependant on the amps you're using. If the amps can be converted to true monoblocks, then you will probably get good performance from them. Check with the manufacturer of what ever amps you're thinking of using and asked them what they recommend.
I also agree with Eldartford about the effects on the power supplies when running the amps in bridged mode. But you need to remember that you are effectively cutting the load seen by the amp in half when running amps in bridged mode. The effects of pulling more on the power supply from one side vs. the other as with the vertical connections can be compensated for by periodically switching the side that drives the woofers. In my brief experience with bridging I have found that the amps run hotter and it just doesn't sound as good. This is very much dependant on the amps you're using. If the amps can be converted to true monoblocks, then you will probably get good performance from them. Check with the manufacturer of what ever amps you're thinking of using and asked them what they recommend.